(W1230-04-21) Assessment of Various Lactobacillus Spp as Potential Candidate for Treatment of Bacterial Vaginosis

Purpose: Bacterial vaginosis(BV) is one of the common Genital tract in inflammations affecting reproductive-age women, with approximately half of these women experiencing abnormal discharge around the world. Over the years, conventional treatments for BV have primarily focused on antibiotics. However, the rise of antibiotic resistance and the increasing interest in alternative, more natural remedies have led to an increased interest in exploring the therapeutic potential of probiotics. Using probiotics in the management of bacterial vaginosis holds great promise as a natural and potentially effective approach. In this study, Lactobacillus spp. (L.gasseri 702820, L.gasseri 70003, L.crispatus 4504, L.crispatus 4505) isolated from the vagina of healthy women was assessed the beneficial probiotic properties to confirm their suitability to treat BV.

Methods: The inhibitory activity of Lactobacillus Spp( L.gasseri 702820, L.gasseri 700003, L. crispatus 4504,  L. crispatus 4504) against BV-associated pathogen(Gardnerella Vaginalis and E.coli 10428) was evaluated using agar diffusion and isothermal microcalorimter. Additionally, the inhibitory effect of both the original and pH modified supernatant of Lactobacillus strains were studied to determine if the inhibition of BV-associated pathogen growth was due to acidic metabolites, using isothermal microcalorimeter. All strains were also assessed for characteristics crucial to BV treatment, including their ability to produce H₂O₂ and acid in simulated vaginal fluid and capacity for self-aggregation and co-aggregation with pathogens.

Results: All strains demonstrated strong inhibitory effects against the Gardnerella Vaginalisand E.coli 10418, with L.gasseri 4505 showing the most significant inhibition. The agar diffusion test indicated that Lactobacillus spp with a good capability to inhibit pathogen. The original supernatant of Lactobacillus spp. showed inhibition to pathogen, suggesting the production of organic acids such as lactic acid, acetic acid, and hydrogen peroxide.  However, inhibition was also observed even when the pH was raised, indicating non-acidic substances also be produced in the process of Lactobacillus spp growing. Three strains (L.gasseri 702820, L.gasseri 70003, L.crispatus 4505) produced) H₂O₂, while L.crispatus 4504 did not. All strains created a highly acidic environment after growth in simulated vaginal fluid and demonstrated ability to elf-aggregation and co-aggregating with Gardnerella Vaginais and E.coli 10418

Conclusion: In conclusion, mixed culture experiments suggested that the growth of G. vaginalis and E.coli 10418 was inhibited to varying degrees by Lactobacillus strains, with L.crispatus 4505 exhibiting the most significant inhibit. Besides, producing H₂O₂ and non-acidic substances, the high capacity for self-aggregation and co-aggregating with pathogenis essential for maintaining a healthy vaginal environment. Therefore, using probiotics in managing bacterial vaginosis holds great promise as a natural and potentially effective approach.

Comparison of power-time curve of co-culture of L.crispatus 4505 and E.coli 10418 in difference concentration. (106: 106CFU/mL, 105: 105CFU/mL, 104: 104CFU/mL)

The power-time curve of A)Gardnerella vaginalis and B) E.coli in original and pH modified supernatants of Lactobacillus strains.

H2O2 produced, Auto-aggregation(%), Co-aggregation(%) and against pathogenic bacteria ability of Lactobacillus strain